Patent documents 1 to 3 disclose a compound having a substructure which is partly the same as that of the compound of the invention and described to be useful as a therapeutic agent for diabetes mellitus.
The compound disclosed in Patent document 2 has a substructure which is partly the same as that of the compound of the invention, however, the structure of the compound disclosed in Patent document 2 is completely different from that of the compound of the invention in that a cyclopropane ring is essential at the α-position of a carboxylic acid.
The compound disclosed in Patent document 3 has a substructure which is partly the same as that of the compound of the invention, however, the structure of the compound disclosed in Patent document 3 is completely different from that of the compound of the invention in that the compound disclosed in Patent document 3 does not have an alkoxy group at the β-position of a carboxylic acid, which is essential to the compound of the invention.